Centrifuge for the clarification of liquids

ABSTRACT

Self-dumping centrifugal separator having a main valve at the periphery of the drum for periodic dumping of solids and a secondary valve for removal of liquid from the separating zone to reduce the discharge of liquid through the main valve during dumping. Means, such as springs, urge the secondary valve into a normally closed position. A control chamber is provided for receiving liquid to urge the secondary valve to the open position and a passageway communicates the control chamber with an annular groove in the drum adjacent the drum axis. The drum includes means for sensing build-up of solids in the solids collecting chamber, including a sensing liquid receiving chamber, having a lower lip and an upper lip, in the drum formed as an annular groove about the drum axis, means for delivering sensing fluid to that chamber and means for delivery of sensing fluid from the chamber to the inner boundary of the solids collecting chamber, and a pulse sensing means projecting into that chamber. The control chamber and the sensing liquid receiving chamber are separated by one of the lips of the sensing liquid receiving chamber. The separating lip is of greater inside diameter than the other lip of the sensing liquid receiving chamber, and the pulse responsive means projects into the sensing liquid receiving chamber to a point radially outward of the inside diameter of the separating lip. Upon build up of the liquid level in the sensing liquid receiving chamber, the pulse responsive means is first contacted and then the liquid overflows into the control liquid receiving chamber. Thereby, the control chamber is filled with liquid which forces the control valve to the open position for discharge of liquid from the separating chamber.

llnited States Patent i191 Hemtort, Jr.

[ 1 CENTRIFUGE FOR THE CLARIFICAT ION OF LIQUIDS [75] Inventor:

[73] Assignee: Westfalia Separator AG, Oelde,

Westfalen, Germany [22] Filed: Apr. 11, 1973 [21] Appl. No.: 350,224

[30] Foreign Application Priority Data Primary ExaminerGe0rge H. Krizmanich Attorney, Agent, or FirmBurgess, Dinklage & i: Sprung 57 ABSTRACT Self-dumping centrifugal separator having a main valve at the periphery of the drum for periodic dump- Heinz llemfort, Jr., Oelde, Germany [111 3,825,176 July. 23, 1974 ing of solids and a secondary valve for removal of liquid from the separating zone to reduce the discharge of liquid through the main valve during dumping. Means, such as springs, urge the secondary valve into a normally closed position. A control chamber is provided for receiving liquid to urge the secondary valve to the open position and a passageway communicates the control chamber with an annular groove in the drum adjacent the drum axis. The drum includes means for sensing build-up of solids in the solids collecting chamber, including a sensing liquid receiving chamber, having a lower lip and an upper lip, in the drum formed as an annular groove about the drum axis, means for delivering sensing fluid to that chamber and means for delivery of sensing fluid from the chamber to the inner boundary of the solids collecting I chamber, and a pulse sensing means projecting into lips of the sensing liquid receiving chamber. The separating lip is of greater inside diameter than the other lip'of the sensing liquid receiving chamber, and the pulse responsivemeans projects into the'sensing liquid receiving chamber to a point radially outward of the inside diameter of the separating lip. Upon build up of the liquid level in the sensing liquid receiving chamber; the pulse responsive means is first contacted and then the liquid overflows into the control liquid receiving chamber. Thereby, the control chamber is ing chamber.

5 Claims, 1 Drawing Figure CENTRIFUGE FOR THE CLARIFICATION F LIQUIDS BACKGROUND The invention relates to an automatically controlled drum centrifuge for the clarification of liquids, having a piston-like valve which periodically opens the apertures through which the solids are discharged, and a chamber located near the drum axis, said chamber being provided, on the side facing the drum axis, with produced by thepulse producing means, the entire content of the drum is ejected through the apertures on the periphery of the drum, so that solids and the liquid mix together again in the catching means surrounding the drum. t

German Pat. No. 1,212,889 discloses a drum centrifuge which, in addition to the main valve for the periodical opening of the peripheral ejection apertures, is equipped with a separately controllable auxiliary valve for the preliminary release of the liquid part of the drum charge. These release apertures are located close to the'outer edge of the platestackand empty into a separate catching means, thereby preventing any backmixing of solids and liquid.

THE INVENTION The invention is addressed to the problem of constructing an automatically controlled drum centrifuge for the clarification of liquids, in such a manner that, when the signal pulse is given to initiate the dumping process, first the far greatest part of the liquid content of the drum will be let out and then the solids which have'collected in the peripheral part of the drum will be ejected.

The invention is characterized by a secondary valve, which is known in itself, for the opening and closing of the apertures for the discharge of the liquid portion of the drum contents; on one side of this secondary valve a plurality of compression springs are distributed around its circumference, and on its other side there is provided a control chamber which communicates through one or more passages with a central annular groove which is separated from the central chamber by an annular wall whose inside diameter is greater than that of the upper boundary of the central chamber and that of the lower boundary of the annular groove and is smaller than the outside diameter of the pulse producing means.

A ring which is under spring bias and is axially displaceable by a control liquid is known, for example, from German Pat. No. 1,182,602. This ring produces the discharge of the'closing liquid from the closing chamber so that the piston-like valve which controls the peripheral apertures for the discharge of the solids and is under the pressure of the contents of the drum, will be able to move into its open position.

An example of the embodiment of the invention is represented in the drawing.

- The drum having separating chamber la'is provided with a main valve'or solids discharge valve 1 for opening and closing the solids discharge apertures 2 for the ejection of the solids. The predetermined level .of the solids in the solids chamber 3 isdetected by a sensing liquid which is fed to the sensing liquid receiving chamber or central chamber 4 through passages 5 and is carried from the outer portion of the chamber 4 through passages 6, 6a, into the solids chamber 3. Passages 6, 6a together form a passageway communicating the sensing liquid receiving chamber with a radially inwardly disposed portion of the solids collecting chamber. ln the central chamber 4 there is provided a pulse producing means 7 which, when the orifices of the passages 6a are covered by separated solids, responds to the displacement of the fluid level that then occurs and delivers a signal pulse to a control apparatus which is not shown.

The drum is equipped with a plate stack 8. Adjacent its outer: margin the drum cover 9 is provided with liquid discharge passages 10 for the discharge of the liquid part of the drumcontents, these apertures being held closed during the centrifuging periods by the secondary sliding valve 11. Bores 12 lead outwardly from the outer bearing surface of thesliding valve 11. On the upperside of the secondary sliding valve 11 a plurality of compression springs 13 are distributed around the periphery, which urge it downwardly during the centrifuging periods, the sealing ring 14 closing the orifices of passages 10. a On'the bottom side of the sliding valve 11 a control chamber 15 is formed which communicates through one or more passages 16 with an annular groove 17 which serves as a control liquid receiving chamber.

The annular groove 17 and the central chamber 4 are serparated from one another by an annular wall or lip 18 whose inside diameter is greater than that of the upper lip 19 of the central chamber 4 and the diameter of the lower lip 20 of the annular groove 17 is smaller than the outside diameter of the pulse producing means 7. The lip 18 is a separating lip separating the sensing liquidreceiving chamber 4 from the control liquid re.- ceiving chamber 17. Y

The drum operates in the following manner. i The liquid, being clarified is delivered to the drum through the infeed tube 21. The'specifically heavier solids collect in the solids chamber3, while the clarified liquid flows away from the side of the plate stack 8 through passages 22, passes over the inside margin of the annular disk 23 into a paring chamber 24 or freely emerges from the drum,'all in known manner. The central chamber 4 is fed through passage '5 with sensing fluid which in this embodiment is tapped from the clear phase and fed through passages 6, 6a, into the solids chamber 3. The passages 10 are held closed by the secondary sliding valve 11 which is under the pressure of the springs 13. As soon as the layer of solids in chamber 3 coversthe orifices of the passages 6a, the free flow of the sensing fluid is impaired and the sensingfluid then backs up in the central chamber 4. The liquid level moving inwardly first reaches the pulse producing means 7 which delivers a signal pulse to a control apparatus which is not shown. This pulse starts the operation of a time-delay relay or thelike, at the end of which the main valve 1 is brought into the open position. At the same time the pulse can also cause valve 25 infeed line 26 to close. Also, the two valves 25 and 27 in the infeed line 26 and outfeed line 28, respectively, may be closed whenever a foreign fluid is used as the sensing fluid.

During the delay time for which the time-delay relay or the like is set, sensing fluid continues to flow to the central chamber 4 and it passes over the inner edge of the partition 18 into the annular groove 17 and through passage 16 into the control chamber 15. As soon as the force acting to open the secondary sliding valve 11 prevails over the spring bias, the sliding valve 11 will be lifted from its seat and most of the fluid content of the drum will be let out through bores and 12.

At the end of the appropriately preset delay time the control apparatus causes the main valve 1 to open for the ejection of the solids. At the same time the orifices of passages 6a are again free and the sensing liquid flows again into the solids chamber 3 of the drum. After the closing of main valve 1 and the opening of the valves in the infeed and outfeed line, the next centrifuging period begins.

SUMMARY Thus, the invention is concerned with a self-dumping drum centrifuge for the separation of a liquid into a so]- ids fraction and a clarified liquid fraction comprising a drum having a separating chamber defined, e.g., by a plate stack such as 8, for the separation, and a solids collecting chamber disposed radially outwardly of the separating chamber. An aperture, eg the passageway 2, is provided at the drum periphery for discharge of solids from the drum periphery, and a solids discharge valve is provided for closing and periodically opening of the ,drum aperture for periodic discharge of solids. The drum is provided with a sensing liquid receiving chamber, e.g., central chamber 4, which is formed as an annular groove about the drum axis, and which has an upper lip and a lower lip. Means are provided for feeding a sensing liquid to the sensing liquid receiving chamber, and a passageway communicates the sensing liquid receiving chamber with a radially inwardly disposed portion of the solids collecting chamber for flow of sensing liquid to the solids collecting chamber. A pulse responsive means is disposed in the sensing liquid receiving chamber for sensing inward displacement of the liquid level in the sensing liquid receiving chamber due to blocking of said sensing liquid feed passageway by solids in the solids collecting chamber and for initiating dumping of solids from the drum. The invention provides the improvement which comprises an aperture for discharge of liquid from the separating chamber to reduce the discharge of liquid during dumping through the aperture for discharge of solids, and a liquid discharge valve, e.g., secondary sliding valve 11, for closing and periodically opening of the liquid discharge aperture in correspondence with the opening of the solids discharge valve to reduce said discharge of liquid during dumping. Means are provided for urging the liquid discharge valve to the closed position. The drum further includes a control chamber for the liquid discharge valve for receiving control liquid to urge the liquid discharge valve to the open position, and a control liquid receiving chamber, such as annular groove .17, in the drum formed as an annular groove about the drum axis. A passageway communicates the liquid discharge valve control chamber and the control liquid receiving chamber. One of the said lips of the sensing liquid receiving chamber separates the sensing liquid receiving chamber and the control liquid receiving chamber, and the separating lip is of greater inside diameter than the inside diameter of the other of said lips, and the pulse responsive means projects into the sensing liquid receiving chamber to a point radially outward of the inside diameter of said separating lip.

What is claimed is:

1. In a self-dumping drum centrifuge for the separation of a liquid into a solids fraction and a clarified liquid fraction comprising a drum having a separation chamber for said separation and a solids collecting chamber disposed radially outwardly of the separating chamber, a solids discharge aperture at the drum periphery for discharge of solids from the drum periphery, a solids discharge valve for closing and periodically opening of the drum aperture for periodic discharge of solids, a sensing liquid receiving chamber in the drum formed as an annular groove about the drum axis having an upper lip and a lower lip, means for feeding a sensing liquid to the sensing liquid receiving chamber, a passageway communicating the sensing liquid receiving chamber with a radially inwardly disposed portion of the solids collecting chamber for flow of sensing liquid to the solids collecting chamber, a pulse responsive means in the sensing liquid receiving chamber for sensing inward displacement of the liquid level in the sensing liquid receiving chamber due to blocking of said sensing liquid feeding passageway by solids in the solids collecting chamber and for initiating dumping of solids from the drum, the improvement which comprises a liquid discharge aperture for discharge of liquid from the separating chamber to reduce the discharge of liquid during dumping through the solids discharge aperture, a liquid discharge valve for closing and periodically opening of said liquid discharge aperture in correspondence with the opening of the solids discharge valve to reduce said discharge of liquid during dumping, means urging the liquid discharge valve to the closed position, means defining a control chamber for the liquid discharge valve for receiving control liquid to urge the liquid discharge valve to the open position, a control liquid receiving chamber in the drum formed as an annular groove about the drum axis, a passageway communicating said control chamber and the control liquid receiving chamber, one of said lips of the sensing liquid receiving chamber being a separating lip separating the sensing liquid receiving chamber and the control liquid receiving chamber, said separating lip being of greater inside diameter than the inside diameter of the other of said lips, and the pulse responsive means projecting into the sensing liquid receiving chamber to a point radially outward of the inside diameter of said separating lip.

2. Centifuge according to claim 1, said control liquid receiving chamber having a lip axially spaced from said separating lip, the inside diameter of separating lip being greater than the inside diameter of said lip of the control liquid receiving chamber.

3. Centifuge according to claim 2, said sensing liquid receiving chamber being disposed above said control liquid receiving chamber.

4. Centifuge according to claim 1, the means urging the liquiddischarge valve to the closed position being a resiliently acting means.

5. Centifuge according to claim 3, the means urging the liquid discharge valve to the closed position being a resiliently acting means. 

1. In a self-dumping drum centrifuge for the separation of a liquid into a solids fraction and a clarified liquid fraction comprising a drum having a separation chamber for said separation and a solids collecting chamber disposed radially outwardly of the separating chamber, a solids discharge aperture at the drum periphery for discharge of solids from the drum periphery, a solids discharge valve for closing and periodically opening of the drum aperture for periodic discharge of solids, a sensing liquid receiving chamber in the drum formed as an annular groove about the drum axis having an upper lip and a lower lip, means for feeding a sensing liquid to the sensing liquid receiving chamber, a passageway communicating the sensing liquid receiving chamber with a radially inwardly disposed portion of the solids collecting chamber for flow of sensing liquid to the solids collecting chamber, a pulse responsive means in the sensing liquid receiving chamber for sensing inward displacement of the liquid level in the sensing liquid receiving chamber due to blocking of said sensing liquid feeding passageway by solids in the solids collecting chamber and for initiating dumping of solids from the drum, the improvement which comprises a liquid discharge aperture for discharge of liquid from the separating chamber to reduce the discharge of liquid during dumping through the solids discharge aperture, a liquid discharge valve for closing and periodically opening of said liquid discharge aperture in correspondence with the opening of the solids discharge valve to reduce said discharge of liquid during dumping, means urging the liquid discharge valve to the closed position, means defining a control chamber for the liquid discharge valve for receiving control liquid to urge the liquid discharge valve to the open position, a control liquid receiving chamber in the drum formed as an annular groove about the drum axis, a passageway communicating said control chamber and the control liquid receiving chamber, one of said lips of the sensing liquid receiving chamber being a separating lip separating the sensing liquid receiving chamber and the control liquid receiving chamber, said separating lip being of greater inside diameter than the inside diameter of the other of said lips, and the pulse responsive means projecting into the sensing liquid receiving chamber to a point radially outward of the inside diameter of said separating lip.
 2. Centifuge according to claim 1, said control liquid receiving chamber having a lip axially spaced from said separating lip, the inside diameter of separating lip being greater than the inside diameter of said lip of the control liquid receiving chamber.
 3. Centifuge according to claim 2, said sensing liquid receiving chamber being disposed above said control liquid receiving chamber.
 4. Centifuge according to claim 1, the means urging the liquid discharge valve to the closed position being a resiliently acting means.
 5. Centifuge according to claim 3, the means urging the liquid discharge valve to the closed position being a resiliently acting means. 